PCBs in the western Mediterranean. Temporal trends and mass balance assessment

Comparison of data reported for polychlorinated biphenyl (PCB) concentrations in different environmental compartments of the western Mediterranean (dissolved and particulate phases of water, sediment and biota) over the last two decades shows a substantial decline in PCB concentrations, which coincides with legislated restrictions in the use of these compounds. Nevertheless, localised chronic (“hotspot”) contamination continues, which underscores the importance of these compounds as environmental contaminants in certain specific areas of the region. n depositional fluxes are used to estimate and model transport processes to investigate the fate of these chemicals in the study area. A tentative mass balance of the compounds suggests that dry and wet deposition (12 t year−1) account for most of the input. This comparess with approximately 1 t year−1 discharged from rivers and sewage outfalls into coastal environments. Sedimentation is estimated to remove 5 t year−1 from the water column. Losses through volatilization are difficult to model owing to the critical dependance within calculations on atmospheric and dissolved seawater concentrations, for which very few data exist.